Republican presidential front runner Donald Trump cancelled a rally in Chicago in the face of huge protests, triggering violent scuffles that prompted criticism from other candidates on the tone of his mass events.

Tension swelled in the sporting arena at the University of Illinois at Chicago last Friday, as a campaign representative informed the crowd that the rally had been cancelled due to security concerns.

Many holding anti-Trump signs such as "Trump = Hate" and "We are not rapists" - referring to Mr Trump's comments on Mexican immigrants - chanted "We dumped Trump", jubilant that their efforts to stop the rally had paid off.

Supporters, though, responded with "We want Trump", hopeful that the brash billionaire would ultimately make an appearance.

But it was not just a war of words. Protesters were seen reaching for Trump campaign posters held by supporters and ripping them in half, and fist fights broke out throughout the arena where an estimated 8,000 to 10,000 people had gathered.

One protester even rushed onto the stage where Mr Trump was expected to speak and tore up a campaign poster as two policemen tried to haul him off.

The ugly scene comes four days before important primary elections in the states of Florida, Ohio, Illinois and Missouri on Tuesday, as Mr Trump seeks to consolidate his pole position in the race for the party nomination.

"I don't want to see anybody hurt," Mr Trump told broadcaster CNN later. "I think we made the right decision (to cancel)... even though our freedom of speech was violated."

Reports say five arrests were made and two police officers suffered injuries - one was hit in the head with a bottle.

Over the weekend, Mr Trump is scheduled to appear at five more rallies and while increased police presence is expected, all eyes will be on how he handles the crowd.

This, however, was not the first time protesters, many of whom are blacks and Latinos angered by Mr Trump's anti-immigrant rhetoric, showed their displeasure with the Republican candidate. Violence has become something of a recurrent theme at Mr Trump's rallies.

Just hours before the Chicago event, clashes broke out in St Louis, Missouri at another Trump rally, where a black man with a bloody nose and a blood-stained white T-shirt was seen stumbling out of the rally.

Last Wednesday, a white Trump supporter punched a black protester as he was being escorted out of a venue, and the night before, a reporter for a news website alleged that Mr Trump's campaign manager assaulted her. Reports say she has since filed charges.

Critics have said that Mr Trump is to blame for the toxic atmosphere surrounding his campaign.

Earlier this month, for example, he encouraged supporters at an Iowa rally to "knock the crap out of them", referring to protesters who had interrupted his speech. He even added that if there were legal fees, he would foot the bill.

But Mr Trump said he did not bear any responsibility for the violence that broke out on Friday.

"I don't take responsibility," Mr Trump told CNN in a phone interview. "Nobody has been hurt at our rallies."

He pushed the blame onto protesters, saying they have been "very abusive" and "overall I think we have been very mild with protesters".

Other candidates, however, have pounced on the chance to point out Mr Trump's failure to unite Americans.

Vermont Senator Bernie Sanders tweeted: "We do things a little different in this campaign: We bring people together."

Florida Senator Marco Rubio said in a CNN interview that Mr Trump should bear responsibility for the "general tone and atmosphere of his campaign" which has pitted groups against each other.

"There are consequences to the things people say in politics," said Mr Rubio. "A president, for example, can't just speak his mind."

Speaking to reporters, Texas Senator Ted Cruz said blame for the events in downtown Chicago rests with the protesters but then added that "in any campaign, responsibility starts at the top".

"When the candidate urges supporters to engage in physical violence, to punch people in the face, the predictable consequence of that is that it escalates. Today is unlikely to be the last such instance," said Mr Cruz.